U.S. patent application number 12/239725 was filed with the patent office on 2009-02-05 for methods and apparatus for polishing an edge of a substrate.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Yufei Chen, Charles I. Dodds, Gary C. Ettinger, Wei-Yung Hsu, Sen-Hou Ko, Donald J. K. Olgado, Ho Seon Shin, Erik C. Wasinger.
Application Number | 20090036042 12/239725 |
Document ID | / |
Family ID | 38656019 |
Filed Date | 2009-02-05 |
United States Patent
Application |
20090036042 |
Kind Code |
A1 |
Shin; Ho Seon ; et
al. |
February 5, 2009 |
METHODS AND APPARATUS FOR POLISHING AN EDGE OF A SUBSTRATE
Abstract
Methods, systems and apparatus are provided for polishing an
edge of a substrate. The invention includes an apparatus adapted to
apply a preset pressure to a polishing film in contact with an edge
of a substrate. The apparatus includes an actuator adapted to apply
a preset pressure to the polishing film; and a controller coupled
to the actuator and adapted to receive a signal indicative of a
condition of the edge of the substrate, and to adjust a pressure
applied by the actuator to the polishing film so as to maintain the
preset pressure based on the received signal. Numerous other
aspects are provided.
Inventors: |
Shin; Ho Seon; (Cupertino,
CA) ; Ettinger; Gary C.; (Cupertino, CA) ;
Olgado; Donald J. K.; (Palo Alto, CA) ; Wasinger;
Erik C.; (Naperville, IL) ; Ko; Sen-Hou;
(Sunnyvale, CA) ; Dodds; Charles I.; (San Jose,
CA) ; Chen; Yufei; (san Jose, CA) ; Hsu;
Wei-Yung; (Santa Clara, CA) |
Correspondence
Address: |
DUGAN & DUGAN, PC
245 Saw Mill River Road, Suite 309
Hawthorne
NY
10532
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
38656019 |
Appl. No.: |
12/239725 |
Filed: |
September 26, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11693695 |
Mar 29, 2007 |
|
|
|
12239725 |
|
|
|
|
60787438 |
Mar 30, 2006 |
|
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Current U.S.
Class: |
451/398 |
Current CPC
Class: |
B24B 57/02 20130101;
B24B 49/16 20130101; B24B 41/067 20130101; B24B 21/002 20130101;
B24B 9/065 20130101 |
Class at
Publication: |
451/398 |
International
Class: |
B24B 5/00 20060101
B24B005/00 |
Claims
1. An apparatus adapted to apply a preset pressure to a polishing
film in contact with an edge of a substrate comprising: an actuator
adapted to apply a preset pressure to the polishing film; and a
controller coupled to the actuator and adapted to receive a signal
indicative of a condition of the edge of the substrate, and to
adjust a pressure applied by the actuator to the polishing film so
as to maintain the preset pressure based on the received
signal.
2. The apparatus of claim 1 wherein the polishing film is adapted
to conform to the edge of the substrate via application of the
preset pressure.
3. The apparatus of claim 1, wherein the signal indicates whether
an endpoint has been reached.
4. The apparatus of claim 1, wherein the signal indicates whether a
layer of material has been removed from the edge of the
substrate.
5. The apparatus of claim 1, wherein the signal indicates whether
an intended edge profile has been reached.
6. The apparatus as recited in claim 1, further comprising: a
driver coupled to the controller adapted to rotate the substrate
against the polishing film, the driver adapted to generate a signal
indicative of the condition of the edge of the substrate.
7. The apparatus of claim 6, wherein the controller is coupled to
and adapted to direct operation of the driver in response to a
signal received from the at least one sensor so as to attain a
preset polish level.
8. The apparatus of claim 1 further comprising a friction sensor
coupled to the controller and adapted to provide a signal
indicative of an amount of friction between the substrate and the
polishing film.
9. The apparatus of claim 8 wherein the amount of friction between
the substrate and the polishing film is indicative of an amount of
material that has been removed from the substrate.
10. The apparatus of claim 6 wherein the signal indicates an amount
of force applied to the actuator to push the polishing film against
the substrate.
11. The apparatus of claim 6 wherein the signal indicates an amount
of energy being exerted to drive the substrate.
12. The apparatus of claim 1 wherein the actuator further comprises
a solenoid.
13. The apparatus of claim 12, wherein the amount of pressure
applied by the actuator is determined based on the amount current
drawn by the solenoid.
14. The apparatus of claim 1 wherein the preset pressure is at
least one of constant or varied.
15. The apparatus of claim 1 further comprising a head adapted to
support the polishing film.
16. The apparatus of claim 15 further comprising a pad mounted to
the head via the actuator, and adapted to press the polishing film
against the substrate.
17. The apparatus of claim 16, wherein the pad is adapted to
contour the polishing film to an edge of the substrate.
18. The apparatus of claim 15 wherein the actuator is adapted to
push the head towards the substrate.
19. The apparatus of claim 16 further comprising a fluid supply
coupled to the controller, wherein a fluid is delivered to the
substrate via the pad.
20. The apparatus of claim 19 further comprising one or more fluid
channels, wherein the fluid channels are adapted to deliver the
fluid to the pad.
Description
[0001] This application is a division of, and claims priority to,
U.S. Non-Provisional patent application Ser. No. 11/693,695, filed
Mar. 29, 2007, and titled, "METHODS AND APPARATUS FOR POLISHING AN
EDGE OF A SUBSTRATE" (Attorney Docket No. 10560), which claims
priority to U.S. Provisional Patent Application Ser. No.
60/787,438, filed Mar. 30, 2006, and entitled "METHODS AND
APPARATUS FOR PROCESSING A SUBSTRATE" (Attorney Docket No.
10560/L). Both of these patent applications are incorporated by
reference herein in their entirety for all purposes.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] Further, the present application is related to the following
commonly-assigned, co-pending U.S. patent applications, each of
which is hereby incorporated herein by reference in its entirety
for all purposes:
[0003] U.S. patent application Ser. No. 11/298,555 filed on Dec. 9,
2005 and entitled "METHODS AND APPARATUS FOR PROCESSING A
SUBSTRATE" Attorney Docket No. 10414); and
[0004] U.S. patent application Ser. No. 11/299,295 filed on Dec. 9,
2005 and entitled "METHODS AND APPARATUS FOR PROCESSING A
SUBSTRATE" (Attorney Docket No. 10121).
FIELD OF THE INVENTION
[0005] The present invention relates generally to substrate
processing, and more particularly to methods and apparatus for
polishing an edge of a substrate.
BACKGROUND OF THE INVENTION
[0006] Conventional systems, which contact a substrate edge with an
abrasive film to clean the edge, may not thoroughly polish or clean
the edge. For example, the abrasive film may not sufficiently
contact both bevels of the edge during cleaning. Additionally, the
abrasive film may become worn from use, and therefore, lose its
ability to sufficiently clean the substrate and require frequent
replacement, which may affect semiconductor device manufacturing
throughput. Accordingly improved methods and apparatus for cleaning
an edge of a substrate are desired.
SUMMARY OF THE INVENTION
[0007] In a first aspect of the invention, a method of polishing an
edge of a substrate is provided. The method includes (1) rotating a
substrate against a polishing film so as to remove material from
the edge of the substrate and (2) detecting an amount of one of
energy and torque exerted in rotating the substrate against the
polishing film. Embodiments of the method further include (3)
determining an amount of material removed from the edge of the
substrate based on the detected energy or torque exerted in
rotating the substrate against the polishing film; (4) ascertaining
a difference between the determined amount of material removed and
a preset polish level; and (5) determining an amount of energy or
torque to be exerted in rotating the substrate adapted to attain
the preset polish level based on the difference between the
determined amount of material removed and the preset polish
level.
[0008] In a second aspect of the invention, an alternative method
of polishing an edge of a substrate is provided. The method
includes (1) rotating a substrate against a polishing film so as to
remove material from the edge of the substrate and (2) detecting an
amount of force exerted in pressing the polishing film against the
substrate. Embodiments of the method include (3) determining an
amount of material removed from the edge of the substrate based on
the detected force exerted in pressing the polishing film against
the rotating substrate; (4) ascertaining a difference between the
determined amount of material removed and a preset polish level;
and (5) determining a level of force to be applied to the polishing
film adapted to attain the preset polish level based on the
difference between the determined amount of material removed and
the preset polish level and adjusting the force to the determined
level.
[0009] In a third aspect of the invention, a system adapted to
polish an edge of a substrate comprising is provided. The system
includes (1) a substrate rotation driver adapted to rotate the edge
of a substrate against a polishing film and (2) a first sensor
coupled to the rotation driver adapted to detect one of an energy
and torque exerted by the substrate rotation driver as it rotates
the substrate against the polishing film. Embodiments of the system
further include (3) a controller coupled to the first sensor and to
the substrate rotation driver adapted to receive from the first
sensor a signal indicative of the detected energy or torque exerted
by the substrate rotation driver and adapted to transmit control
signals to the substrate rotation driver based on the detected
energy or torque exerted.
[0010] In a fourth aspect of the invention, an apparatus adapted to
apply a preset pressure to a polishing film in contact with an edge
of a substrate is provided. The apparatus includes (1) an actuator
adapted to apply a preset pressure to the polishing film and (2) a
controller coupled to the actuator and adapted to receive a signal
indicative of a condition of the edge of the substrate, and to
adjust a pressure applied by the actuator to the polishing film so
as to maintain the preset pressure based on the received
signal.
[0011] Other features and aspects of the present invention will
become more fully apparent from the following detailed description,
the appended claims and the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0012] FIG. 1 is a schematic illustration of a cross-section of a
portion of a substrate.
[0013] FIG. 2 is a schematic illustration depicting an example
embodiment of an edge cleaning apparatus according to the present
invention.
[0014] FIGS. 3A and 3B are close-up front and side cross-sectional
schematic views, respectively, of a portion of the edge cleaning
apparatus of FIG. 2.
[0015] FIG. 4 is a perspective view depicting an example embodiment
of an edge cleaning apparatus according to the present
invention.
[0016] FIG. 5 is a perspective view depicting another example
embodiment of an edge cleaning apparatus according to the present
invention.
[0017] FIG. 6 is a perspective view of a portion of the example
embodiment depicted in FIG. 5.
[0018] FIGS. 7A and 7B are close-up perspective views of different
embodiments of replaceable cassettes for use with embodiments of
the present invention.
[0019] FIGS. 8A through 8C are close-up perspective views of
different embodiments of pads for use with embodiments of the
present invention.
[0020] FIGS. 9A through 9C are plan views of examples of different
possible head positions of the example edge polishing apparatus of
FIG. 4.
[0021] FIGS. 10A through 10C are plan views of examples of
different possible head positions of the example edge polishing
apparatus of FIG. 5.
[0022] FIG. 11 is a perspective view of an embodiment of a multiple
head edge polishing apparatus according to the present
invention.
[0023] FIG. 12 is a perspective view of another embodiment of a
multiple head edge polishing apparatus according to the present
invention.
[0024] FIG. 13 is a perspective view of yet another embodiment of a
multiple head edge polishing apparatus according to the present
invention.
[0025] FIG. 14 is a schematic illustration depicting an example
embodiment of an edge cleaning apparatus according to the present
invention.
DETAILED DESCRIPTION
[0026] The present invention provides improved methods and
apparatus for cleaning and/or polishing the edge of a substrate.
With reference to FIG. 1, a substrate 100 may include two major
surfaces 102, 102' and an edge 104. Each major surface 102, 102' of
the substrate 100 may include a device region 106, 106' and an
exclusion region 108, 108'. (Typically however, only one of the two
major surfaces 102, 102' will include a device region and an
exclusion region.) The exclusion regions 108, 108' may serve as
buffers between the device regions 106, 106' and the edge 104. The
edge 104 of a substrate 100 may include an outer edge 110 and
bevels 112, 114. The bevels 112, 114 may be located between the
outer edge 110 and the exclusion regions 108, 108' of the two major
surfaces 102, 102'. The present invention is adapted to clean
and/or polish the outer edge 110 and at least one bevel 112, 114 of
a substrate 100 without affecting the device regions 106, 106'. In
some embodiments, all or part of the exclusion regions 108, 108'
may be cleaned or polished as well.
[0027] The present invention provides a frame for supporting a film
(e.g., an abrasive polishing film) or abrasive buffer against the
edge 104 of a substrate 100 as the substrate 100 is rotated (e.g.,
by a vacuum chuck, drive rollers, etc.). The film may be pressed
against the rotating substrate edge 104 using a pad pushed by an
actuator and/or an inflatable pad. In either case, the pad and/or
inflatable pad may be soft and/or include or develop contours to
conform with the shape of the substrate edge 104. Depending on the
amount of force applied by the actuator, the resiliency of the pad
selected, the amount of inflation of an inflatable pad, and/or the
amount of tension on the film, a controlled amount of pressure may
be applied to polish the edge 104. Alternatively or additionally,
the film may be under tension within the frame such that the film
itself is adapted to apply a variable amount of tension to the
substrate edge 104 and to contour to both the outer edge 110 and at
least one of the bevels 112, 114 (e.g., with or without additional
support from a pad). Thus, the present invention provides precise
control of an edge polish process which may be used to compensate
for different edge geometries and changes in the substrate 100 as
material is removed from the edge 104.
[0028] In some embodiments, the frame may support multiple
polishing heads, each head being adapted to support polishing film.
The polishing heads may support different types of films (e.g.,
films of different abrasive grits) which may be used concurrently,
in a predefined sequence, or at different times. The heads may be
disposed in different positions and in different orientations
(e.g., aligned with the edge 104, normal to the edge 104, angled
relative to the edge 104, etc.) to allow the supported films to
polish different portions of the edge 104 of the rotating substrate
100. The heads may be adapted to be oscillated or moved (e.g.,
angularly translated about a tangential axis of the substrate 100
and/or circumferentially relative to the substrate 100) around or
along the edge 104 by the frame so as to polish different portions
of the edge 104. In some embodiments, the heads may continuously
oscillate around or along the rotating edge 104 of the substrate
100. Each head may include an indexed spool of film and/or be
contained in a replaceable cassette. An indexed spool may allow a
precise amount of film to be advanced to position unused film for
polishing. In some embodiments, two indexed spools may be used to
allow film to be moved back and forth between the spools.
[0029] Additionally or alternatively, the present invention may
include facilities to deliver fluids to the substrate edge 104
being polished. In some embodiments, one or more channels may be
provided to direct chemicals or water to the substrate edge 104 to
assist in the polishing and/or to wash away particles resulting
from the polishing. The chemicals may be sprayed directly onto the
substrate 100, at the substrate/polishing film interface, and/or
may be applied to and/or through the film and/or pad. The fluids
may be sprayed from either or both sides of the substrate 100 and
the present invention may employ gravity or suction to cause the
runoff not to contaminate or contact other parts of the substrate
100 or apparatus of the invention. Further, energy (e.g., megasonic
energy) may be applied to the substrate edge 104 via fluid carrying
such energy.
[0030] The substrate 100 may be rotated in a horizontal plane. The
edge 104 of the substrate 100 may be aligned with or normal to the
polishing film, pad, and/or polishing head. In additional or
alternative embodiments, the substrate 100 may be rotated in a
vertical plane, other non-horizontal plane, and/or be moved between
different planes of rotation.
[0031] In some embodiments, the driver(s) used to rotate the
substrate 100 and the actuator used to push the pad and/or
polishing film against the substrate edge 104 may be controlled by
a controller. Likewise, operation of the indexed spool(s) and/or
the fluid channels may also be under the direction of a controller.
The controller may be adapted to receive feedback signals from the
driver and/or actuator that indicate: (1) an amount of energy
and/or torque being exerted to drive the substrate 100 (e.g.,
rotate a vacuum chuck holding the substrate 100) and/or (2) an
amount of force applied to the actuator to push the pad/polishing
film against the substrate 100, respectively. These feedback
signals may be employed to determine an amount of material that has
been removed from the edge of the substrate 100, which may include,
for example, whether a particular layer of material has been
removed and/or whether an intended edge profile has been reached.
For example, a reduction in the torque of the rotating substrate
100 (or energy expended in rotating the substrate 100) during a
polishing procedure may indicate a reduction in friction between
the substrate 100 and the polishing film and/or pad. The reduction
in torque or rotational energy may correspond to an amount of
material removed from the edge of the substrate 100 at or near
points of contact between the substrate 100 and the polishing film
and/or a characteristic edge profile (e.g., a shape, curvature or
smoothness level at the edge of the substrate 100).
[0032] Alternatively or additionally, a friction sensor positioned
in contact with the edge of the substrate may provide signals
indicative of an amount of material that has been removed from the
substrate 100.
[0033] Turning to FIG. 2, a schematic view of an edge polishing
apparatus 200 is depicted. A frame 202 supports and tensions a
polishing film 204 in a plane perpendicular to the major surfaces
102, 102' of a substrate 100 such that the edge 104 of the
substrate 100 may be pressed against (e.g., as indicated by the
straight downward arrows 205a, 205b) the polishing film 204 and the
polishing film 204 may contour to the substrate edge 104. As
indicated by the curved arrow 205c, the substrate 100 may be
rotated against the polishing film 204. The substrate 100 may be
rotated at a rate ranging from about 50 to 300 RPM, for example,
although other rates may be used. The substrate 100 may contact the
polishing film 204 for about 15 to 150 seconds depending on the
type of film used, the grit of the film, the rate of rotation, the
amount of polishing required, etc. More or less time may be used.
In some embodiments, the polishing film 204 may be supported by a
pad 206 disposed adjacent a backside (e.g., a non-abrasive side) of
the polishing film 204 and mounted on the frame 202. As indicated
by the straight upward pointing arrow 207, the frame 202 including
the tensioned polishing film 204 and/or the pad 206 may be pushed
against the edge 104 of the substrate 100. In some embodiments, the
substrate 100 may be pushed against the polishing film with an
amount of force ranging from about 0.5 lbs. to about 2.0 lbs. Other
amounts of force may be used.
[0034] Additionally or alternatively, an additional length of the
polishing film 204 may be supported and tensioned by spools 208,
210 mounted to the frame 202. A supply spool 208 may include unused
polishing film 204 available to be unwound and pulled into position
adjacent the substrate 100 while a take-up spool 210 may be adapted
to receive used and/or worn polishing film 204. One or both of the
spools 208, 210 may be indexed to precisely control the amount of
polishing film 204 that is advanced. The polishing film 204 may be
made from many different materials including aluminum oxide,
silicon oxide, silicon carbide, etc. Other materials may also be
used. In some embodiments, the abrasives used may range from about
0.5 microns up to about 3 microns in size although other sizes may
be used. The abrasives may also be of different shapes and
textures. Different widths of polishing film 204 ranging from about
1 inch to about 1.5 inches may be used (although other widths may
be used). In one or more embodiments, the polishing film may be
about 0.002 to about 0.02 of an inch thick and be able to withstand
about 1 to 5 lbs. of tension in embodiments that use a pad 206 and
from about 3 to about 8 lbs. of tension in embodiments without a
pad. Other films having different thicknesses and strengths may be
used. The spools 208, 210 may be approximately 1 inch in diameter,
hold about 500 inches of polishing film 204, and may be constructed
from any practicable materials such as polyurethane, polyvinyl
difloride (PVDF), etc. Other materials may be used. The frame 202
may be constructed from any practicable materials such as aluminum,
stainless steel, etc.
[0035] In some embodiments, one or more fluid channels 212 (e.g., a
spray nozzle or bar) may be provided to deliver chemicals and/or
water to aid in the polishing/cleaning of the substrate edge 104,
lubricate the substrate, and/or to wash away removed material. The
fluid channel 212 may be adapted to deliver fluid to the substrate
100, to the polishing film 204, and/or to the pad 206. The fluids
may include deionized water which may serve as a lubricant and to
flush particles away. A surfactant and/or other known cleaning
chemistries may also be included. In some embodiments, sonic (e.g.,
megasonic) nozzles may be used to deliver sonicated fluids to the
substrate edge 104 to supplement the cleaning. Fluid also may be
delivered through the polishing film 204 and/or pad 206 to the edge
104.
[0036] Turning to FIGS. 3A and 3B, close-up front and side
cross-sectional schematic views, respectively, of the polishing
film 204 and pad 206 of FIG. 2 are depicted. Note that the forces
(indicated by the straight arrows) cause the polishing film 204 and
the pad 206 to contour and conform to the edge 104 of the substrate
100. In some embodiments, if the substrate 100 was not present, the
pad 206 would have a flat surface where the substrate 100 is shown
compressing the pad 206. Likewise, if the substrate 100 was not
present, the polishing film 204 would lie flat and be represented
by a straight line in both views.
[0037] Turning now to FIGS. 4 and 5, two additional alternative
embodiments of an edge polishing apparatus 400, 500 are depicted.
As shown in FIG. 4, an example edge polishing apparatus 400 may
include a base or frame 402 that includes a head 404 which supports
polishing film 204 tensioned between spools 208, 210 and further
supported by a pad 206. As shown, the pad 206 may by mounted to the
head 404 via a biasing device 406 (e.g., a spring). The edge
polishing apparatus 400 of FIG. 4 also may include one or more
drive rollers 408 (two shown) and guide rollers 410 (two shown)
that are adapted to rotate the edge 104 of the substrate 100
against the polishing film 204. The drive rollers 408 may
themselves each be driven by drivers 412 (e.g., motors, gears,
belts, chains, etc.).
[0038] The drive rollers 408 and guide rollers 410 may include a
groove that allows the rollers 408, 410 alone to support the
substrate 100. In some embodiments the groove within the drive
rollers 408 may have a diameter of approximately 2.5 inches and the
groove within the guide rollers 410 may have a diameter of
approximately 1 inch. Other dimensions are possible. The area of
the drive rollers 408 in contact with the substrate 100 may include
texturing or cross-grooves to allow the drive rollers 408 to grip
the substrate 100. The drive rollers 408 and guide rollers 410 may
be constructed from materials such as polyurethane, polyvinyl
difloride (PVDF), etc. Other materials may be used.
[0039] As shown in FIG. 5, another example edge polishing apparatus
500 may include a base or frame 502 that includes a head 504 which
supports polishing film 204 tensioned between spools 208, 210 and
further supported by a pad 206. As shown, the pad 206 may by
mounted to the head 504 via an actuator 506 (e.g., a pneumatic
slide, hydraulic ram, servo motor driven pusher, etc.). The edge
polishing apparatus 500 of FIG. 5 also may include a vacuum chuck
508 coupled to a driver 510 (e.g., motor, gear, belt, chain, etc.).
An advantage of the embodiment depicted in FIG. 5 is that the
apparatus 500 does not need to contact the edge 104 being polished.
Thus, the potential of particles accumulating on drive rollers and
being re-deposited on the edge 104 is eliminated. The need to clean
rollers also is eliminated. Further, the possibility of rollers
damaging or scratching the edge is also eliminated. By holding the
substrate in a vacuum chuck, high speed rotation without
significant vibration may be achieved.
[0040] Turning now to FIGS. 6 through 8B, some details of features
of the example embodiments of FIGS. 4 and 5 are described. Note
that features from the different embodiments may be combined in
many different practicable ways to serve different design
principals or concerns.
[0041] FIG. 6 depicts details of the frame 502 including the head
504 of FIG. 5. As described above, a head 504 supports polishing
film 204 tensioned between spools 208, 210. The frame 502 (that
includes head 504) may be adapted to be angularly translated
(relative to an axis that is tangential to the edge 104 of a
substrate 100 held in the edge polishing apparatus 500 (FIG. 5)) by
a driver 600 (e.g., a servo motor) and pivot 602. The angular
translation of the frame (and polishing film 204) is described in
more detail below with respect to FIGS. 9A through 10C.
[0042] Additionally, the spools 208, 210 that are mounted to the
head 504, may be driven by one or more drivers 604 (e.g., servo
motors). The drivers 604 may provide both an indexing capability to
allow a specific amount of unused polishing film 204 to be advanced
or continuously fed to the substrate edge, and a tensioning
capability to allow the polishing film to be stretched taught and
to apply pressure to the substrate edge.
[0043] As can more clearly be seen in FIG. 6 (as compared to FIG.
5), the optional pad 206 may by mounted to the head 504 via an
actuator 506 that is adapted to adjustably press and contour the
polishing film 204 against a substrate edge 104 (FIG. 5). Further,
one or more support rollers 606 may also be mounted to the head 504
to guide and align the polishing film 204 in a plane perpendicular
to the major surface 102 (FIG. 1) of a substrate 100 held in the
edge polishing apparatus 500 (FIG. 5).
[0044] Note that in the embodiment depicted in FIGS. 5 and 6, the
length of the polishing film 204 is disposed orthogonal to the edge
104 of a substrate 100 being polished. This is in contrast to the
embodiment depicted in FIG. 2, wherein the longitudinal direction
of the polishing film 204 is aligned with the edge 104 of a
substrate 100 being polished. Other polishing film orientations and
configurations may be employed. For example, the polishing film 204
may be held diagonally relative to the major surface 102 of the
substrate 100.
[0045] Turning to FIGS. 7A and 7B, close-up perspective views of
two different embodiments of replaceable cassettes 700A, 700B are
depicted. Cassettes 700A, 700B may be adapted to provide the
features of the head 404 and polishing film 204 in a disposable,
refillable, and/or replaceable package which may be quickly and
easily mounted on and/or removed from the frames 402, 502 of
different edge polishing apparatuses 400, 500.
[0046] As shown in FIG. 7A, the cassette 700A may include head 404
which supports polishing film 204 which spans from supply reel 208
to take-up reel 210. The polishing film 204 may be guided and
aligned by support rollers 606 mounted to the head 404. A pad 206
may be provided to further support the polishing film 204 as
described above. Also as described above, a biasing device 406
(e.g., a spring) may be employed to mount the pad 206 to the head
404 to provide flexible, dynamic counter-pressure to the pad 206.
Alternatively or additionally, an adjustable actuator 506 (FIG. 6)
may be used to push the pad 206 against the polishing film 204 or
to push the entire head 404 toward the substrate 100.
[0047] In yet another alternative embodiment, as shown in FIG. 7B,
instead of a pad 206, the head 404 may simply rely on the tension
of the polishing film 204 to provide lateral pressure to the
substrate edge 104 (FIG. 1). In some embodiments, the head 404 may
include a notch 702 as shown in FIG. 7B to accommodate the
substrate 100.
[0048] Turning to FIGS. 8A and 8B, two different alternative
embodiments of pads 206A, 206B are depicted. In addition to a pad
206 (FIG. 6) that has a flat surface co-planar with the polishing
film 204 when a substrate is not present, a pad 206A may include a
concave surface that matches the contour of the edge 104 of a
substrate 100. Alternatively, as shown in FIG. 8B, the pad 206B may
include a double concave surface to better match the contour of the
edge 104 of a substrate 100. In yet other alternative embodiments,
a pad 206 may include a shaped groove that precisely matches the
contour of the edge 104 of a substrate 100 including the bevels
112, 114 and outer edge 110 (FIG. 1).
[0049] The pads 206, 206A, 206B may be made of material such as,
for example, an acetal resin (e.g., Delrin.RTM. manufactured by
DuPont Corporation), PVDF, polyurethane closed cell foam, silicon
rubber, etc. Other materials may be used. Such materials may have a
resilience or an ability to conform that is a function of the
thickness or density of the pad. The material may be selected based
upon its resilience, which, in turn, may be selected based upon the
type of polishing required.
[0050] In some embodiments, the pad 206, 206A, 206B may have an
adjustable amount of ability to conform to the substrate's edge.
For example the pad 206, 206A, 206B may be or include an inflatable
bladder such that by adding more air or liquid or other fluid, the
pad becomes harder and by reducing the amount of air or liquid or
other fluid in the bladder, the pad becomes more conforming. FIG.
8C depicts an embodiment of a pad 206C that includes an inflatable
bladder 802 that may be filled (and/or emptied) via a fluid channel
804 with fluid from a fluid supply 806. In some embodiments, the
fluid supply 806 may inflate/deflate the bladder 802 under the
direction of an operator or a programmed and/or user operated
controller. In such embodiments, an elastomeric material such as
silicon rubber or the like, may be used for the bladder 802 to
further enhance the pad's ability to stretch and conform to the
substrate's edge 104. Such an embodiment would allow an
operator/controller to precisely control how far beyond the bevels
112, 114 (if at all) and into the exclusion region 108 and/or 108'
(FIG. 1) the polishing film 204 is made to contact the substrate
100 by, e.g., limiting the amount of fluid pumped into the bladder
802. For example, once a substrate outer edge 110 is placed against
a pad 206C with a deflated bladder 802, the bladder 802 may be
inflated so that the pad 206C is forced to wrap around and conform
to the outer edge 110 and bevel(s) 112, 114 of the substrate 100
without wrapping around to the device region 106, 106' of the
substrate 100. Note that in some embodiments, multiple bladders may
be used in a pad and that differently shaped inflatable bladders
may be used within differently shaped pads 206, 206A, 206B.
[0051] In some embodiments, fluids used to aid in the polishing may
be delivered to the substrate edge via the pads 206, 206A, 206B. A
fluid channel may be provided to drip or spray the fluid on or into
the pads. Alternatively, an inflatable pad may include a bladder
with a semi-permeable membrane that allows fluid to be slowly
released and transmitted to the polishing film 204 (e.g., through
the pad). In such embodiments, the pads 206, 206A, 206B may be
covered by, made of, and/or include material that absorbs and/or
retains the fluids used (e.g., polyvinyl alcohol (PVA), etc.).
[0052] FIGS. 9A through 9C and FIGS. 10A through 10C depict
examples of different possible head positions of the alternative
edge polishing apparatuses 400, 500 respectively, described above.
The present invention is adapted to bring polishing film 204 in
contact with the bevels 112, 114, and outer edge 110 of a substrate
100 without contacting the device region 106 of the substrate 100.
In operation, this is achieved by angularly translating a head 404,
504 (and consequently, a portion of polishing film in contact with
and contoured to the edge 104 of a substrate 100) around an axis
that is tangential to the outer edge 110 of the substrate 100 as it
is rotated. Referring to FIGS. 9A through 9C and FIGS. 10A through
10C, this axis of angular translation may be represented by a line
extending perpendicular out of the paper upon which the FIGs. are
drawn at the point labeled "P." The heads 404, 504 may be held in
various positions to clean desired portions of the substrate edge
104 as the substrate 100 is rotated. In some embodiments, the heads
404, 504 may be adapted to continuously or intermittently oscillate
between the various positions depicted and/or other positions. The
heads 404, 504 may be moved on the frame 502 by drivers 600 (FIG.
6) under the direction of a programmed or user operated controller.
Alternatively, the heads 404, 504 may be fixed and/or only adjusted
while the substrate is not being rotated. In yet other embodiments,
the substrate may be held fixed while the heads are oscillated (as
described above) as well as rotated circumferentially around the
substrate 100. Further, the polishing film 204 may be mounted on
the heads 404, 504 in a continuous loop and/or the polishing film
204 may be continuously (or intermittently) advanced to polish
and/or increase the polishing effect on the substrate edge 104. For
example, the advancement of the film 204 may be used to create
and/or enhance the polishing motion. In some embodiments the film
204 may be oscillated back and forth to polish and/or enhance the
polishing effect on a stationary or rotating substrate 100. In some
embodiments, the film 204 may be held stationary during polishing.
Further, the film 204 tension and/or force 207 (FIG. 2) may be
varied based on various factors including, for example, the angle
and/or position of the polishing film 204, the polishing time, the
materials used in the substrate, the layer being polished, the
amount of material removed, the speed at which the substrate is
being rotated, the amount of current being drawn by the driver
rotating the substrate, etc. Any combination of the above described
polishing motions and/or methods that are practicable may be
employed. These methods provide additional control over the edge
polish process which can be used to compensate for geometry and
changes in the material being removed as the film 204 is
rotated/move about or relative to the edge 104.
[0053] Turning to FIGS. 11 through 12, additional embodiments of an
edge polishing apparatus are depicted. FIG. 11 depicts an edge
polishing apparatus 1100 including three heads 404, FIG. 12 depicts
an edge polishing apparatus 1200 including two heads 504, and FIG.
13 depicts an edge polishing apparatus 1300 including four heads
1304. As suggested by the drawings, any number and type of heads
404, 504, 1304 may be used in any practicable combination. In
addition, in such multi-head embodiments, each head 404, 504, 1304
may used a differently configured or type of polishing film 204
(e.g., different grits, materials, tensions, pressures, etc.). Any
number of heads 404, 504, 1304 may be used concurrently,
individually, and/or in a sequence. Different heads 404, 504, 1304
may be used for different substrates 100 or different types of
substrates. For example, a first head 404 with a stiff biasing
device 406 supporting a pad 206 such as the concave pad 206B and a
coarse grit polishing film 204 may initially be used to remove a
relatively large amount of rough material from the substrate bevels
112, 114 (FIG. 1). The first head 404 may be appropriately
positioned to access the bevels 112, 114. After cleaning with the
first head 404 is completed, the first head 404 may be backed away
from the substrate 100, and a second head 504 with a fine grit
polishing film 204 (and without a pad) may be moved into position
to polish the bevels 112, 114 and the outer edge 110.
[0054] After cleaning one or more substrates 100, the portion of
the polishing film 204 employed for such cleaning may become worn.
Therefore, the take-up reel 210 (FIG. 4) may be driven to draw the
polishing film 204 by a fixed amount from the supply reel 210 (FIG.
4) toward the take-up reel 210. In this manner, an unused portion
of the polishing film 204 may be provided between the take-up reel
210 and supply reel 208. The unused portion of the polishing film
204 may be employed to subsequently clean one or more other
substrates 100 in a manner similar to that described above.
Consequently, the apparatus 1100, 1200 may replace a worn portion
of polishing film 204 with an unused portion with little or no
impact on substrate processing throughput. Likewise, if replaceable
cassettes 700A are employed, impact on throughput may be minimized
by quickly replacing the cassettes 700A when all the polishing film
204 in the cassette 700A is used.
[0055] Regarding the example embodiment of an edge polishing
apparatus 1300 of FIG. 13 specifically, a frame 1302 that supports
multiple heads 1304 is depicted in schematic form. The heads 1304
are each mounted to the frame 1302 and each include an actuator
1306 (e.g., pneumatic piston, servo driven slide, hydraulic ram,
etc.) adapted to press a pad 206 and a length of polishing film 204
against the edge 104 of a substrate 100 in response to a control
signal from a controller 1308 (e.g., a programmed computer, an
operator directed valve system, an embedded real time processor,
etc.). Note that the controller 1308 is coupled (e.g.,
electrically, mechanically, pneumatically, hydraulically, etc.) to
each of the actuators 1306.
[0056] In addition, a fluid supply 806 may be coupled to and under
the control of the controller 1308. The fluid supply 806 may be
controlled to independently deliver fluids (e.g., DI water,
cleaning chemistry, sonicated fluids, gas, air, etc.) to each of
the heads 1304 via one or more fluid channels 212. Under the
direction of the controller 1308, various fluids may be selectively
delivered to the pads 206, the polishing film 204, and/or the
substrate edge 104 via the fluid channels 212. The fluid may be for
use in polishing, lubricating, particle removal/rinsing, and/or
inflating a bladder 802 (FIG. 8C) within the pads 206. For example,
in some embodiments, the same fluid delivered through a permeable
pad 206 may be used for both polishing and inflating the pad 206
while a different fluid, delivered to the same head 1304 via a
second channel (not shown) is used for rinsing and lubricating.
[0057] Turning to FIG. 14, a schematic view of an embodiment of the
present invention similar to the example edge polishing apparatus
200 of FIG. 2 is depicted. As with the embodiment of FIG. 2, a
frame 202 supports and tensions a polishing film 204 in a plane
perpendicular to the major surfaces 102, 102' (FIG. 1) of a
substrate 100 such that the edge 104 of the substrate 100 may be
pressed against (e.g., as indicated by the straight downward arrows
205a, 205b) the polishing film 204 and the polishing film 204 may
contour to the substrate edge 104. As indicated by the curved arrow
205c, the substrate 100 may be rotated against the polishing film
204. The polishing film 204 may be supported by a pad 206 disposed
adjacent a backside of the polishing film 204 and mounted on the
frame 202. As indicated by the straight upward pointing arrow 207,
the frame 202 including the tensioned polishing film 204 and/or the
pad 206 may be pushed against the edge 104 of the substrate 100.
The polishing film 204 may be supported and tensioned by spools
208, 210 mounted to the frame 202. A supply spool 208 may include
unused polishing film 204 available to be unwound and pulled into
position adjacent the substrate 100 while a take-up spool 210 may
be adapted to receive used and/or worn polishing film 204. One or
both of the spools 208, 210 may be indexed to precisely control the
amount of polishing film 204 that is advanced. One or more fluid
channels 212 may be provided to deliver chemicals and/or water to
aid in the polishing/cleaning of the substrate edge 104, lubricate
the substrate, and/or to wash away removed material. The fluid
channel 212 may be adapted to deliver fluid to the substrate 100,
to the polishing film 204, and/or to the pad 206.
[0058] The embodiment of FIG. 14 further includes a controller 1308
(e.g., a software driven computer, a programmed processor, a gate
array, a logic circuit, etc.) adapted to direct the operation of a
driver 1402 which may be used to rotate the substrate 100. The
driver 1402 may be embodied, for example, as a motor adapted to
rotate a vacuum chuck, drive rollers, etc. The controller 1308 may
transmit or output a control and/or power signal to the driver 1402
via a signal line 1404. Further, the controller 1308 may be adapted
to receive one or more feedback or information signals from the
driver 1402 via one or more signal lines 1406. As noted above, the
feedback or information signals from the driver 1402 may provide
various indications about the status of the driver 1402, the edge
polishing apparatus 202, and/or the substrate 100. For example, the
rotational speed of the driver 1402 may be determined from a signal
that indicates the amount of current drawn by a motor within the
driver 1402. Alternatively, a sensor (not shown) within the driver
1402 may be employed to generate a signal indicative of the torque
of the platform (e.g., vacuum chuck) holding the substrate 100 as
it is rotated by the driver 1402 and/or the energy being exerted by
the driver 1402 to rotate the substrate 100 via the platform.
[0059] The information signal(s) on the signal line(s) 1406 may be
used to monitor the polishing progress of the edge polishing
apparatus 202. For example, a change in the current drawn by a
motor within the driver 1402 as indicated by a feedback signal on
signal line 1406 may be interpreted by the controller 1308 as an
indication that the amount of friction between the edge polishing
apparatus 202 and the substrate has changed. Assuming a constant
force 207 is being maintained by the edge polishing apparatus 202
on the substrate 100, the controller 1308 may interpret the change
in the amount of friction to mean that different material is now
being polished. A substrate 100 that includes multiple layers of
material including, for example, a film layer, may be comprised of
different materials. Thus, the controller 1308 may determine that
the change in current indicated on the signal line 1406 means that
a layer of material has been removed from (e.g., polished off of)
the edge 104 of the substrate 100. Additionally or alternatively,
depending on the characteristics of the edge 104 of the substrate
100, the controller 1308 may interpret a change in the amount of
friction to mean that a certain amount of material has been removed
from the edge 104 and consequently, that the edge profile has
changed.
[0060] The embodiment of FIG. 14 further includes an actuator 1408
adapted to be directed by the controller 1308. The actuator 1408
may be used to press the pad 206 and/or film 204 against the
rotating the substrate 100. The actuator 1408 may be adapted to
apply a constant force against the substrate or a variable force
determined by the controller 1308. The actuator 1408 may be
embodied, for example, as a pneumatic piston, a hydraulic ram, an
electric solenoid, etc. The controller 1308 may transmit or output
a control and/or power signal to the actuator 1408 via a signal
line 1410. Further, the controller 1308 may be adapted to receive
one or more feedback or information signals from the actuator 1408
via one or more signal line(s) 1412. The feedback or information
signals from the actuator 1408 may provide various indications
about the status of the actuator 1408, driver 1402, and/or the
substrate 100. For example, the amount of force applied by the
actuator 1408 may be determined from a signal that indicates the
amount of current drawn by a solenoid within the actuator 1408.
Alternatively, a sensor (e.g., a transducer, not shown) within the
actuator 1408 may be employed to generate a signal indicative of
the energy being exerted by the actuator 1408 to apply force to the
substrate 100.
[0061] As with the information signal(s) on signal line(s) 1406,
the signal(s) on line(s) 1412 may be used to monitor the polishing
progress of the edge polishing apparatus 202. For example, as
material is removed from the substrate 100 and the diameter of the
substrate 100 is reduced, an actuator 1408 adapted to automatically
maintain a fixed amount of force on the substrate 100 may adjust
the position of, and/or applied force to, the pad 206 and/or
polishing film 204. A signal on line 1412 may indicate this change
and the controller 1308 may make a determination that a certain
amount of material has been removed from (e.g., polished off of)
the substrate 100 based on the signal.
[0062] The controller 1308 may use the feedback signals provided by
the driver 1402 to determine whether a preset endpoint for edge
polishing has been reached (e.g., a desired edge profile) and/or a
difference between a current state of the edge 104 and the preset
endpoint. For example, if the endpoint has been reached or the
current state of the edge 104 is close to the endpoint (e.g., as
measured in an amount of material that has been removed from the
edge 104), then the controller 1308 may transmit signals to the
driver 1402 to reduce the rotation speed of the substrate 100 so as
to, in the former case, prevent further removal of material from
the edge 104 or, in the latter case, to decrease the rate at which
material is removed from the edge 104. Similarly, the controller
1308 may use feedback signals provided by the actuator 1408 to
determine whether the preset endpoint has been reached or is close
to being reached. The controller 1308 may transmit signals to the
actuator 1408 to reduce an amount of force applied to the pad 206
and/or polishing film 204 to halt or slow removal of further
material from the edge 104 in the event of such a
determination.
[0063] The foregoing description discloses only exemplary
embodiments of the invention. Modifications of the above disclosed
apparatus and methods which fall within the scope of the invention
will be readily apparent to those of ordinary skill in the art. For
instance, although only examples of cleaning a round substrate are
disclosed, the present invention could be modified to clean
substrates having other shapes (e.g., a glass or polymer plate for
flat panel displays). Further, although processing of a single
substrate by the apparatus is shown above, in some embodiments, the
apparatus may process a plurality of substrates concurrently.
Further, the edge polishing apparatus 200 of the present invention
may be integrated to other devices. For example, the apparatus 200
may be integrated into a major surface polisher or a substrate
cleaner. Integrating a edge polishing module into an output station
of a substrate polisher (e.g., the APPLIED MATERIALS, INC.
Reflexion Oxide CMP System) exchanger offers a number of
advantages. Such integration can take advantage of the substrate
exchanger so that no additional substrate transport is required.
Facilities such as de-ionized water and drains are already resident
and access to the module through the polisher windows may be easily
available. Additionally, such integration may be done without
impacting the footprint of the tool. Further, particularly with
applications which have relatively long process cycle times such
as, for example, copper applications, there is sufficient time to
polish the edges of the substrate without degrading the overall
throughput of the tool.
[0064] Accordingly, while the present invention has been disclosed
in connection with exemplary embodiments thereof, it should be
understood that other embodiments may fall within the spirit and
scope of the invention, as defined by the following claims.
* * * * *